Amino Acids: while much of the hype surrounding amino acids are related to amino acid supplementation, amino acids themselves are relatively basic components of sound nutrition, and easily obtained through whole food sources.
Amino acid supplementation- a trendy for of supplementation popular with bodybuilders and average gym goers alike- is often used in the hope of aiding muscle growth and recovery. However, few of those supplementing with amino acid blends or single amino acids truly know much about how amino acids work individually and in concert with other amino acids in the human body.
One such amino acid, Tyrosine, is particularly misunderstood.
What is Tyrosine?
Tyrosine is a non-essential amino acid. Meaning? Amino acids are basic building blocks for protein. Amino acids are classified as either essential or non-essential.
Essential amino acids (of which there are nine) are amino acids that cannot be synthesized in the human body. As such, essential amino acids must be consumed through diet. Non-essential amino acids, on the other hand, can be synthesized in the human body.
Tyrosine is a non-essential amino acid that can be synthesized from phenylalanine, an essential amino acid. Tyrosine serves as a precursor to two important neurotransmitters: dopamine and norepinephrine. Tyrosine is also crucial to the structure of nearly every protein in the human body.
L-Tyrosine Acts as a Precursor to Neurotransmitters
L-tyrosine serves as a precursor to several important neurotransmitters, including- most notably- dopamine and norepinephrine. Neurotransmitters are chemical substances released by nerve fibers that produce impulses to other nerve fiber, muscle fiber, or structure in the human body.
In the absence of neurotransmitters, nerves would lack the ability to direct impulses, deliver signals, or capitalize action. Simple movements would become impossible, and underlying physiological processes (for example, sleep patterns) would cease to work effectively.
Dopamine- an important neurotransmitter produced by tyrosine- plays a crucial role in the direction and coordination of the body’s various physical movements and actions. Dopamine also plays a potent role in the brain’s motivation and reward systems. For this reason, dopamine is often highly involved in patterns of addiction.
However, addictive patterns are not the only conditions where a disruption in typical dopamine patterns is noted. Parkinson’s disease, a degenerative disease characterized by tremors and loss of coordination and ability to move, is caused by the loss of neurons in the brain responsible for the development and production of dopamine.
Norepinephrine- another crucial neurotransmitter produced by tyrosine- helps the body maintain a sense of alertness. For this reason, norepinephrine is highly involved in the body’s fight or flight response, providing the brain and body with the ability to react to situations in which the body is at risk of imminent peril. In times of high stress or danger, norepinephrine keeps the body on high alert.
Established L-Tyrosine Benefits
Given its classification as an amino acid, tyrosine plays many important roles in the human body. Some of these are thanks to its role as a precursor to neurotransmitters, while others are due to its role in protein structure and formation. Still, others are not yet fully understood.
Phenylketonuria
Also known as PKU, Phenylketonuria is one of the most common disorders of amino acid metabolism. Individuals with PKU inherit it thanks to a genetic defect in an enzyme known as phenylalanine hydroxylase or PAH. PAH converts phenylalanine to tyrosine in the human body.
A deficiency of this enzyme results in dangerously low levels of tyrosine and an excess of phenylalanine in the bloodstream and the body’s various tissues. Untreated PKU causes serious and irreversible brain damage, intellectual disabilities and impairments, behavioral disorders, and seizures.
Luckily, standardized newborn blood testing is responsible for the diagnosis of nearly all existing cases of PKU. Treatment of PKU typically involves a diet low in phenylalanine, as to reduce the likelihood of phenylalanine accumulating in the bloodstream and various tissues.
Because PKU results in a deficiency of tyrosine, most individuals with PKU are treated with amino acid supplements containing tyrosine: these supplements are specifically formulated for their unique condition.
Individuals with PKU should always consult a doctor before self-prescribing any dietary supplements or medications, given the potentially life-threatening nature of this condition.
Mental performance
While acute stress is something regularly experienced in response to a situation, such as traffic or a big work presentation, chronic stress is becoming a common problem, especially for busy and overworked Americans. Chronic stress can reduce immunity, increase inflammation, and cause difficulties in concentration, memory, and daily function.
A number of studies have shown that supplementation with tyrosine can reduce mental impairments related to the stress response, including mood and task performance. Other studies have shown that tyrosine supplementation improves working memory during task performance and aids in the ability to effectively switch from one task to another without diminished performance.
Memory
Through its role as a precursor to neurotransmitters dopamine and norepinephrine, tyrosine may work to improve working memory, even in challenging or stressful conditions.
One study found that impairments in working memory caused by environmental exposure to extreme cold were successfully reduced by treatment with tyrosine.
Other studies have echoed this sentiment, showing that impairments in working memory caused by physically or mentally challenging situations may be alleviated with tyrosine supplementation.
Alertness
Through its precursor role to Norepinephrine — a neurotransmitter highly involved in the fight or flight response — tyrosine provides the body and the brain with the ability to remain alert and active. In high-stress situations, an increase in norepinephrine primes that body and the brain with the ability to act quickly.
Studies have shown that tyrosine supplementation may increase alertness, even in fatigued or sleep-deprived subjects. However, while a high level of alertness has its advantages, it also has its marked disadvantages.
Chronically high levels of norepinephrine can become problematic, leading to fatigue and disturbances and sleep.
Possible L-Tyrosine Benefits
While tyrosine has many well-recognized benefits, scientific studies continue to evolve and identify possible areas of human health in which tyrosine may play a role. Given its classification as an amino acid and neurotransmitter precursor, it is not unlikely that tyrosine plays many as of yet discovered roles in the human body.
Attention Deficit Disorder
Although the causes of attention deficit disorder and attention deficit hyperactive disorder (ADD and ADHD, respectively) are not fully understood, some scientists theorize that amino acid treatments may improve concentration in individuals with these conditions. Given that norepinephrine (for which tyrosine is a precursor) improves alertness and mental task performance, it’s not a far-reaching assumption.
However, research in this area has been decidedly mixed and limited: available studies have shown only very limited or temporary improvements, while others have shown no improvements at all. This is likely because studies have not shown a large association with tyrosine abnormalities and attention deficit disorders.
Depression
Very little is known about the effects of tyrosine on depression, anxiety, or other mental health disorders and conditions. While neurotransmitter disruption may play a role in depression for certain individuals, the causes and factors contributing to depression are multiple and complex.
Most studies have shown that tyrosine supplementation does not improve symptoms of depression in a clinical trial. However, research in this area is very limited.
Physical Performance
Interestingly, while tyrosine has been shown to improve cognitive performance as related to working memory, cognitive flexibility, and task performance, tyrosine supplementation has not been shown to improve physical performance in general tasks or feats of athleticism. However, some studies have shown that tyrosine may provide some small benefit in sports-related concentration.
Dementia and Alzheimer’s Disease
Certain degenerative diseases (including dementia, Alzheimer’s disease, and Parkinson’s disease) show a reduction in neurotransmitter activity in the brain. In an effort to improve concentrations of neurotransmitters in patients with degenerative conditions, some trials have examined the effects of amino acid precursor supplementation. While some impact has been shown, studies are still very limited and further research is needed.
Schizophrenia
Very little is known about the causes of schizophrenia, a mental disorder characterized by impairments in thinking, behavior, and feeling. Common symptoms include hallucinations, hearing voices, delusions, and other severe and impacting beliefs or thoughts that impair the ability to function normally. Schizophrenia is very difficult to treat, and effective medications are few.
While tyrosine has been studied as an adjunct treatment in schizophrenia, studies are very few, and little improvement has been shown. However, some scientists theorize that issues of tyrosine transport may play a role in schizophrenia.
Tyrosine Supplements
Tyrosine is available both in whole food and supplement forms. Tyrosine supplements are increasingly popular both as individual supplements and in amino acids blends, which are commonly used in sport/athletic supplementation.
While supplementation is undoubtedly popular, it’s important to remember that dietary supplements are not regulated by the Food and Drug Administration (FDA), as they are considered neither food nor drug. The self-regulating dietary supplement industry is incredibly prone to errors in labeling and issues of contamination, potency, and undeclared ingredients. For this reason, nutrients consumed in whole food form are almost always a safer and healthier option.
The Recommended L-Tyrosine Dosage
Dosing is highly dependent upon the individual receiving treatment, other medication, and dietary supplements, and the condition being treated. There is no one recommended dose for tyrosine supplements. However, tyrosine supplements have been given in doses of 100-300 mg/kg for mental performance, 150-300 mg/kg for memory, and 150 mg/kg for alertness.
However, given the potential for l-tyrosine dosage to negatively interact with other medications or supplements, not self-dosing is key. Even if you are not consuming other supplements or medications, always consult a doctor before self-prescribing or self-dosing a supplement.
How Does Tyrosine Interact With Medication
As is true for any dietary supplement, tyrosine may interact negatively with other medications and dietary supplements. This is especially important for individuals with thyroid disorders or those being treated with medication for thyroid function, as tyrosine may cause an excess of thyroid hormones. Tyrosine also interacts with medications affecting the regulation of dopamine, such as Levodopa.
Where to Buy Tyrosine
Tyrosine supplements can be purchased either as an individual supplement or in a blend with other amino acids or micronutrients. Supplements may be purchased at specialized supplement stores, pharmacies, or grocery stores. Always consult a doctor before purchasing or consuming a supplement, especially if you are taking the supplement in an effort to treat a specific condition.
If this is the case, your physician may be able to prescribe a more effective, pharmaceutical grade supplement.
Tyrosine-Rich Foods
Remember that it is almost always better to consume nutrients in their whole food form rather than in a supplement. Whole protein-rich foods provide a vast array of nutrients, many of which affect the absorption of other nutrients. For this reason, nutrients consumed in whole food form may be better absorbed and utilized by the body.
Tyrosine is found in many protein-rich foods. Foods high in tyrosine include (but are not limited to): cheese, beef, milk, fish, eggs, beans, pumpkin seeds, pork, turkey, and chicken.
The L-Tyrosine Side Effects
Side effects of tyrosine supplements may include (but are not limited to) nausea, headache, heartburn, and gastrointestinal upset. There is not enough data to determine the safety, tolerability, or potential side effects of tyrosine supplementation in pregnant women or young children.
For this reason, pregnant women and parents should always discuss supplementation with a doctor before supplements are either consumed by a pregnant woman or given to a child.
Tyrosine: Where to Go From Here
Tyrosine is an important, albeit non-essential amino acid that can be synthesized in the body through the consumption of essential amino acid phenylalanine. Tyrosine plays an important role in the formation of various neurotransmitters, making it somewhat indispensable in its role in cognition, memory, alertness, and task performance. In addition to its role as a neurotransmitter, tyrosine plays an important role in protein structure.
While many scientists theorize that tyrosine may hold additional benefits in areas of memory, cognition, and diseases of neural degeneration, research is ongoing. In the meantime, focus on consuming tyrosine in whole food forms. Tyrosine is readily available for consumption in an array of high protein whole foods, making sufficient consumption relatively simple.
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